Train controd



March 26, 1929. w. D. HAIILES TRAIN CONTROL Filed Nov. 26, 1924 Patented Mar. 26, 192a UNITED stares P T-Eur errrce.

WILLIAM DQ'HEI IIE S; OF ROCHESTER, NEWYURK ASSIGNOR'TOGENERKL'RKIEWAY SIGNAL COMPANY, OF ROCHESTER} NEWYORK.

TBQAZIN CONTROIM Application filed November 26',.1924. Serial New 752,338. 1,

This invention relates 'to automatic train trol influences from thetrackway to a l'llOV- ingzvehicle. In the type of system embodying the present invention, this COlnnlUlllCfllllOIhlS acconniilished by 1I1QtDS"0f two alternating currentsflowing in the track'rails-o'r other suitable trackway conductors, and inducing: correspondingcurrents-in collecting coils carried by the vehicle: The alternatingzcontrol currents flowing inthe track railsare displaced in phaselrelation, and the various distinctive intluences are' transmitted byv means of the reversal of the instantaneouspolarity 'of one of these currents, and the absence of eitheu one'or both et these cunrentsa V In the practical-application ofsuch a sys lJOlll OlE' the continuous inductive type to railways, it istound, thatiir order to n'iaintainx the proper mechanical clearance between the car-carried IGCGiVGI'S and the-trackway equip- Y inentf, the air gapthrough which the-inductive influences must act is comparatively large and for this reason the current induced in the caucarriedreceivers is very small. Ino'rder that this Weak current may properly operate the car-carriedequipment, it is essential that some amplifying. means he used, and the' vacuum tube or audion type of amplifier has been found to belbest suitedl'or this purpose. 7

In the type of 2113i1pllll(31'I10\V 1nuse, tWo sets of vacluun tubesor audionsrare usedto amplify the control currents collected by, the tvto sets or"- receiving. coils, these tubes being, supplied with. platecurrent .El'OIlI acoinnion' sourceusually a suitable dircctcurrent generator or ijlyuaniotor, and their-filaments beingrheated by aconnnon battery or'other suitable source of energy. The output: of these twosets oi audions is impressed upon the two phase windings off a suitable polyphase relay which operates the car-carried control. apparatus; In the usual type of amplifier, it'has been found that the energiza of one of these sets of receiving coils alone produces a variationor fluctuation in the plate voltagessupplied to the amplifier, andthat this variation in plate voltage results in a vtn iation in the plate current in the first tube of thede-energized amplifier and, when a transformer is: used 'in the: plate circuit, irnpresses-avariationiin grid potential upon-the second tube of this amplliier, and so: gives rise. toan. alternating current in the output:

circuit -and a consequent. fiOW of current, in the: phase of the relayuvhich should be de energized. For various reasons, this current in the presumably tie-energized phase. of the relay nay not be in phase Withthe current in the energized'phase, and if, these tWoicur-rents are out of phase, a torque in the relaywill result, sometimes causing. a false operation thereof'f- The fluctuation of the plate-voltage niayrarise from commutaton ripplesas Well as tromvariation in' loads.

WVith the above and otherconsiderations iii-mind, it is proposed' in. accordance With the present invention to providean improved amplifier for use in connection Withacontina lions-inductive train control system in which fluctuation in the plate voltage will not result irra false :energization otthe relay;

h Other objects, advantages .and characteristicfeatures of thepresent invention. will become apparentas the description thereof progresses.

In t-hedrawings, the amplifier embodying the presenttinvention has been shown ina diagrannnatic and--conventional inauner, together With a silnplifiedshoiving of the track- Way and.carscarriedequipment of a typical train control systein of thecontinuous inductive type. a a

Tie: amplifier coniprising the present invention may be used with any: suitable type of traclmvay circuits and control devices, the systemish own being ofthe usual threerposition type embodying two control currents; thetracltpliase current flowing in the two tracltlrails in serics andthe line phase current,-fioivin in tllCl'WO track rails in multiple. These control currents are impressed on the track rails of the usual insulated blocks, of which the block-I and theeiuls oi the twoadjacent blocks Hand J have been shown, these currents being supplied. from a transmission line. 1 through transformers 2 and3, andbeing controlled by the usual track relays 4. located. at the entrance end of the pedance coils 6 asshown in the track phase circuits. The track relays 4 are energized from the usual track batteries 5, located at the exit ends of the blocks,thecurrents from these neous polarity ott the line phase current in the batteries being shunted away from each track relay when a train is locatedin the block with which this relay is associated by the wheels and axles of such train. From an inspection of the drawings,it'is evident that the deenergizationof the track relay tot agiven block "will cause a reversal of the instantacblock next in the rear withreferenc'eito the normal direction oftralfic which is indicated I by the arrow.

A railway vehicle has been conventionally represented in the block H by the wheels and axles 7. This vehicle is provided with the usual collecting or receiving'coils, represented at 8 and 9, wh1ch are mounted w1th or without iron cores and in. inductive relation to the track rails. The track and line phase'control currents flowing in the track rails induce corresponding voltages in the receiving coils, and

these voltages are impressed on' the input circuits 01'? the two amplifiers which comprise the present inventlon. The output circuitsof these amplifiers are connected to the two -windings 10 and 11 of ajpolyphase car relay trol practice.

MR of the type now common in the train'con- YThe relaycMR may' b ejused to operate suitable contact fingers such as the fingers 12 and 13 shown, and to control circuits 'for various su table car-carr ed apparatus by means of these fingers and their associated'stationary fieontacts. In the present instance, cab signals G Y and B have been shown,represcnt- Ting clear, caution a nd dangerjtraffic conditions, thesecab signals being preferably in I devic'es'used for thispu'rpose in train control systems.

I V eu s illustration, two brake control 'l dances and /LB have been shown, it being assumed that the device I-IB acts in' some suitable manner f to impose a mediumspeed restrictionupon the de-energization'ota circuit through its windings,"andthat-the device I'll; acts to impose minimumspeed restriction upon the de-v energization of its circuit. The circuits for the brake control "device are c'ontrolledby the contact finger'13 of the relay MR and athese'circuits may, be readily traced in the Referring now' more particularly to the amplifying device comprising the present inventiomthis device is composed of two amplifiers, of two stages each, one. amplifier T being arranged'to amplify thetracl: phase volt- {ages induced in, thecoils 8, and the other circuit is obvious from the drawings.

,amplifier 'L to amplify the line phase voltages induced in the coils 9. As these amplifiers are identical in every detail, a description of the line phase amplifier L only will be given, the corresponding parts of the track phase amplifier T being designated by like reference characters having distinctive exponents;

' The voltage induced in the receiving coils 9 is impressed across the grid and filament of the first tube 14 through a circuit which may be traced as follows :-From the receiving coils 9, wires 15 and 1G to the grid 17 of the tube 1 1, through the filament 18,

through the resistance unit 19 and the ballast lamp 20 in series, wires 21, 22 and 2?) to the receiving coils 9. The receiving coils 9 are tuned to resonance for maximum voltage at the frequency oi the alternating control current by means of the condenser 2 1 connected across these coils as clearly shown. The filaments 18 and 25 of the two audions Hand 26 are connected in series and are heated by a single battery 27 through a circuit including the usual current limiting resistance 19 and the ballast lamp 20, which A voltage is impressed between the filaments 18 and 25 and the plates 28 and 29 of the two tubes let and 26 by means of a direct current generator G, through parallel circuits including the iron core impedance coils 30 and 31 as clearly shown. The impedance ofthe coils 30 and 31 is of a high value, these coil impedances being preferably from 7 to lO'times the value of the internal impedance ofthe tubes for reasons which will become apparent as the description of the amplifier progresses. it is evident that the filaments and the plate circuits of the tubes 14 and 26 of thetrack phase amplifier T :Hl also supplied with energy from the battery 27 and the generator G.

The output of the first tube 14 is impressed upon the primary winding 38 ot' a suitable transformer, in the present instance, an autotransformer 33, through a circuit which is traceable as follows From the plate 28 of the tube 1st, wires 3.. and 35, blocking condenser 36, wire 37, primary winding 38 of the autotransformer 33, wires 39, 40 and 21, ballast lamp 20, and resistance 19 to the filament 18 of the tube 14. The secondary winding of the transitorn'ier 33 is connected to the grid circuit of the second tube 26 through the tol lowing circuit:From the grid 32 of the tube 26, wires and 43, through the secondary winding 11 of the autotranstormer 33,wires 39, 40 and 21, ballast lamp 20 and resistance 19, the filament 18 of the tube 1-1, and wire 44 tothe filament- 25 of the tube 26. The secondary winding of the transformer 33 is tuned to resonance at the frequency of the control current by means of the condenser 51; connected as shown, this tuning being racemes sometimesproduced by the commutator ripples of this generator, and these fluctuations may produce a false operation of the relays it not: properly tuned out.

The output circuit of the second tube 26 is connected to the Windin 11 of the polyphase relay MR through a blocking condenser L7, this circuit being obvious from the drawingsi 0pcratio'it id itli both track and? line phase currents flowing in the traclr rails, the two sets 01' receiving coils 8* and 9 have alternating voltage-s induced tl1e1'ein,and voltages are'iiiipressed upon the grid and filament circuits of the tubes 14; and 14 of the amplifiers L and T respectively. These alternating voltages are anipliiiedby the tubes 14 and M in the-usual nianner and areiinpressed on the primary windings of the trans formers and 33 through the bl ckingcondcnsersgfl and 36 these blocking condensers serving to prevent the direct current coini'onent iron'i the'plate circuits from passing through the transformer windings. 'lhe alternating voltages impressed upon the trans- :toriiier's arestepped up and impressed oii the grid circuits of the tubes 26 and 26 and these voltages are again amplified and impressed on the windings of the relay MR, through the blocking condensers 457 and 4:7 and circuits Which are obvious. Since the two alternating control currents flowing in the track rails are displaced in phase relation aspointed out above, the two amplified alternating currents flowing in the windings l0 and 11 of the relay MR are also displaced in phase relation, and a torque is produced in this relay in the usual manner, causing the contact lingers 10 and 11 to swing to the positions shown and to control the apparatus as described above.

Under danger traiiic conditions, that is, with the train under consideration travclii'ig iii a block in which another train or other danger condition is located, the line phase current only is flowing; in the track rails, the

:mmliticr L alone is ei'icruized and the relay i i suoulu be de-enczgrizcd. As the Voltaire oi: a generator fluctuates with a fluctuation in l ad, the varying current drawn bythe plate circuit of ti: .vliiier ii causes a fluctuation in the ternumti voltage of the generator G, which in turn caur-ics a fluctuation in the voltage impr "ed across impedance coil 80 and the first b h 41 of the tack phase amplitier T. Orr Ly, with the usual type of aniplfiii'er, this r'luctuatioii oi. the voltage in the plate c cuit of the first tul of the amplifier i on bya -anstoriner located 't, and a uld cause a Variseed on the grid sweet car-carried circuit of the second tube 526 thereby iniressin an alternating current from the arepliiier '1 on the relay winding 10. Thisialse orcross-ieed curreiih as it is sometimes called if out of phase with the current iinpresset upon the relay Winding 11 by the amplifier L, produces a torque in the relay which may result in its oiicration, so giving a clear or caution indication under danger conditions.

With the amplifier en1bodyingthe present involition, however, the grid circuit of the second tube-26 ofthe uncnergized auipliticr T is shielded from the fluctuation of the generator voltage by thc'high impedance oi the coil 30 which tends to cholzc out such fluctuations before they reach the primary wil'iding 38 of the transformer 83 Viewed in a different manner, the impedance oi the coils 30, 31, 30 and 31 is very high as compared with the internal iitipe'dancc of the tubes used, and for this reason, the voltage drop across the tube lt and the primary winding 2:38 oi tl transformer 33 will l" very small ascouiparcd \vitlrthe voltage I across the coil 30", and'thereitore a very small fluctuation in Voltage will passed on throughthe traus'torincr33 tothegi'id circuit of the second tube 26 As the primary of the traustorin "r 33' is connected directlyacross the p e and iiiaiueiit teruiifuais oi? thetube choke coil 30, but it should, be obs rved that fvariations in voltage acrossthc tube itself caused by the alternating voltage inipressed on it's-grid circuit from the collect iug coils 9, are directly iinpr ssed upon the transformer 33 so that the tube and choke combination of the present inventioitmay be said to pass on a maximum Voltage from the grid circuit while clicking bafcl-c to a large extent, thevoltagge due to'iiuctuations in the plate circuit.

It is sometimes found that fluctuations or variations appear iii the plate circuit voltage due to the characteristics of the generator used to supply this voltage, such as commutator ripples or variations due toniechanical vibration. It is'evident from t 1e discussion given above that such fluctuation would produce a false operation or the relay or an unreliabletransi'i'1isf-?ion of control influences 'lriuu the tracirway ii the usual type of amplilicr were used, but With the arrangement embodying the present invention, these fluctuations are choked out by the llllPLCltUlCC coils as eiqilaincd above and do not materially affect the operation of the relay.

It is obvious that ia onneeting the grid circuit of the second tube directly across the first tube, the voltage amplification Whic can be obtained from tlie'first stage oi amplification is dependent on the amplification characteristics of the tube used; In the a1npliiier embodying the present invention, the

it, the Variations in generator voltage are absorb-ed by the voltage obtained from the first tube 1 L is stepped up bymeans of the transformer 33 beforebeing impressed upon the grid circuit of the second'tube 26, so-that an eificientvoltage {LHIPlIfiCElt-lOIl may be obtained irom the ffirsi; stage.

v Theline phase current, however, will be substantially constant throughout the entire block. These unequal currents-may produce a faulty operation of the car relay due to the fact that the stronger control current, flowing in one amplifier, produces fluctuations in v the plate generator voltage in the manner described above, and these fluctuations, if applied to the other amplifier, may oppose the control current in such amplifier, thus weak enin the current in one abuse of the rela to such an extent that no torque will be produced or reversing the phase relation between the currents and so giving a false indication. In

theamplifier arrangement of the present in vention, the fluctuation produced by the heavily energized phase cannot be impressed on the Weakly energized phase because of the shielding efiect of the impedance coils and 3 0? as described above, and for this reason,

got the relay must "also be in phase in order that no torque wlll be produced in the relay.

false relayroperation as aresultof unequal control currentsis avoided. 4o

Amplifiers for use withtrain control systemsmust beba'lanced as to the constants of the1r various circuits in order to prevent false operation of the. relays. That is, wlien two alternating volt-ages which are exactly in i Jhase are im Dressed u on the two am )lifiers the currents whieh flow in'the two windii s This condition is particularly necessary when an unbalanced line phase control current flows 1n the two track rails 1n multiple, 111(l11C-- ing voltages which are in phase in each oil the receiving coils. In the usual type of amplifier, in order to. transfer thcse alternating control currents without phase displacement,

' the constants of the amplifier circuits must be uniform, and the various circuits must be carefully tuned. Due to the wide variation existing between the constants of commercial tubes of a given type, ithas be en found that in the ordinary type 01 ampl her, when a tube was changed due to breakage or other failure, v the constants of the amplifier circints are so changed that the'condition of balance would not be mainta ned, and amplifier has to be tuned every time a new tube was in ser ed. In the amplifier comprising the present invention, this diiliculty is eliminated by reason of the fact that the impedance of the tube is very small as compared with the im- )QCliLDCE of the choke coils in the plate circuit, and hence a small change in the impedance of a given tube produces a negligible not change in the constants of the entire plate circuit. Because of this relation between tube and coil constants, the tubes may be interchanged without the necessity of rebalancing the amplifier, and the internal tuning of the amplifier may be dispensed with.

The amplifier of the present invention is particularly adapted for use with automatic train control systems for several reasons. It will not produce a false operation 0'! the relay when one phase alone is energized. Commutator ripples or fluctuations in plate voltage arising from any other source will not be amplified or impressed on the relay windings, whereas the impressed voltage received from the track rails will be efiicicntly amplified. Commercial variations in circuit constants, such variations caused by the interchanging of tubes, will not materially allect the operation of the amplifier.

As the amplifier of the present invention .has been shown and described in a, rather specific form, it should be clearly umlcrstood that theinvention is not limited to the form shown, and thatvarious changes, additions and modifications could be made within the scope of the appended claims without departing from the spirit of the invention.

hat it is desired to secure by Letters Patentis 1. In an automatic train control system. means for amplifyin current inductively received from the trackway comprising, two audion tubes, inductive receiving means connected between the grid and filament of one of said tubes, a circuit c mncctingthe plate and filament of said tube including in series a direct current generator and means for reducing voltage fluctuations, a second circuit connect lg the plate and filament of said tube including the primary winding of a transformer, and a tuned circuit connecting the grid and filament of said second tube including the secondary winding of said transformer, whercbv the voltage lluctuatimis of saiddirectcurrent generator are not transmitted from the plate and filament circuit of said first tube to the grid and filament circuit of said second tube.

2. In an automatic train control system. means tor amplifying current inductively received from the traclrway conun'ising a plurality of audion tubes. inductive receiving means connected between the grid and filament oi one of said tubcs'and means for connecting said tubes in cascade comprising cirsuits connecting; the plates and filaments of i l i l ii each of said tubes including in series a direct current generator and an iron core impedance coil, a second circuit connected between the plate and filament of one of said tubes including the primary winding of a transformer, and a tuned circuit including the secondary winding of said transformer connected between the grid and filament of an other of said tubes.

3. In an auton'iatic train control system, car-carried means for receiving and ampliiying control currents comprising two sets of receiving coils connected by tuned circuits to the grid and filament elements oi two andion tubes, two parallel circuits connected to the plate and filament elements oi each of said two tubes, one of saidcircuits including the primary winding of a transformer and the other of said circuits including an impedance coil and a common source of potential, and a circuit connected between the grid and filament elements of each of two other audiontubes, and each including in multiple the secondary winding of one oi said transformers and a variable condenser.

i. in an automatic train control system, means for collecting and amplifying two inductively received control currents comprising, two sets or receiving coils, connected respectively with the grid and filament circuits of two audion tubes, transformers having their primary windings connected across the plate and filament circuits of said two audion tubes and their secondary windings tuned and connected to the grid and filament circuits of two other audion tubes respectively, circuits including a source of continuous potential connected in parallel respectively with the plate and filament cir cuits of all of said audion tubes, and impedance coils connecting said potential circuits to the plates of said tubes, said impedance coils being included in said potential circuits only.

5, In an automatic train control system, means for collecting and amplifying two inductively received control currents comprising, two sets of receiving coils, connected respectively with the grid and filament circuits oi. two audion tubes, transformers having their primary windings connected across the plate and filament circuits of said two audion tubes and their secondary windings tuned and connected to the grid and filament circuits ol two other audion tubes respectively, circuits including a source ct continuous potential connected in parallel respectively with the plate and filament circuits of all of said audion tubes, and impedance coils included in said potential circuits only.

6. In an automatic train control system, means for amplifying current inductively received from ti'ie trackway comprising, two

auoion tubes, inductive receiving means con .nccted between the grid and filament of one of said tubes, a circuit connecting the plate and lilamentot said tube including in series a directcurrent generator and means, having an impedance several times as great as that of a said tube, for reducing voltage fluctuations, a second circuit connecting the plate and filfllntllt said tube including the primary winding of a. transformer, and a tuned circuit connecting the grid and filament of said second tube including the secondary winding of said transformer, whereby the voltagefluctuations of said direct current generator are not transmitted from the plate and filament circuit oi said first tube to the grid and filament circuit of said second tube.

In testimony whereof I ai'hx my signature.

' i WILLIAM D. HAILES. 

